Kinahan — On Granite and Metamorphic Rocks. 245 



In general these eurytes are ignored for building purposes, on 

 account of the far-famed sandstones of the county being preferred ; 

 yet they are a good, effective, permanent stone, as seen, for instance, 

 in the Coastguard station at Cushendall, Co. Antrim, where an 

 identical euryte was used, as hereafter mentioned. 



There are also a few dykes of whinstone in the Silurian rocks, 

 but, as a general rule, these are used only for road metal. 



Within the Slieve Grallion district [metamorphosed Arenig, or 

 Cambrian) there is a granite very similar to that of Omey Island, 

 Co. Galway, which is evidently newer than the associated schist, 

 but older than the Pomeroy series {Llandovery (?) ) ; and there are 

 granites and elvans which seem to be the root-rocks of the inter- 

 stratified Silurian eurytes. The older granite could be raised in 

 large blocks, and is suitable for ornamental purposes ; but the 

 Silurian granites, although often a handsome red stone, are nearly 

 always so much jointed that they could only be procured in stones 

 of small dimensions. 



The Hornblende-rock is greatly varied in character. In general 

 it is very coarsely crystalline ; but sometimes it is a fine blackish or 

 grey hornblendic granite. In this tract there are Ophytes and 

 Ophito-hornblendic rocks, some of the latter being very like the 

 so-called "Swedish green granite." These rocks appear capable 

 of being utilized for ornamental purposes. The localities in which 

 they occur have been given in the description of the ophytes (vol. v., 

 p. 407). 



In the metamorphosed Ordovicians, west, south-west, and 

 south-east of Castlederg, there are protrudes and courses of horn- 

 blende rock, as also to the westward of Sion, a little N.E. of 

 Newtownstewartj on the S.E. slope of Bessy Bell, and a few miles 

 S.W. of Gortin, in Ballynatub mountain, (g. s. m.) 



Within the schist district, as about Strabane, Castlederg, and 

 elsewhere, this rock is ordinarily used for common buildings. As 

 to character it varies from fine argillaceous to more or less 

 gneissose. Near Castlederg the surface is covered with many 

 loose blocks of this micaceous rock, which are used for building. 

 They are frequently split by an ingenious application of fire on 

 the top of the stone, the expansion resulting from which is made to 

 separate the stone in any part required." ( Wilkinson) 



